The key to this functionality is a new Windows Phone feature called Linked Inbox. It's a feature of Windows Phone 7.5, the most recent version of the Windows Phone OS, and is thus available on all currently shipping devices and, via a free upgrade, to all original generation devices as well. Linked Inbox provides a special integrated view of multiple email accounts. That is, you can continue to access your individual email accounts separately, as you were forced to do in the original version of Windows Phone. But you can also optionally link two or more accounts into a single view, called a linked inbox.

The Linked Inbox feature is useful for a number of reasons. For example, if you configure three email accounts on the phone, you'll get three different Start screen tiles, one for each account, and will need to check for, write, and manage email in those three separate instances of the Windows Phone mail app. That's fine for some people, perhaps even preferable. But for many others, a single view makes more sense. Many just want to deal with email, not with individual accounts. And Linked Inbox is how you get there.

Configuring Linked Inbox

To use Linked Inbox, you configure your email accounts as always. Then, you access the tile for one of the email accounts you'd like to link, tap the More app bar button ("...") and then Link Inboxes. Then, from the list of available email accounts, pick one or more other email accounts to link. Optionally, rename the set of linked inboxes and then tap Done.

Now, you'll see a new linked inbox tile on your Start screen that uses the name you chose. When you access this app, you'll see an integrated view that combines the contents of each account's inbox. You can read email, manage it (such as by deleting or moving to new folders), and create new email. Each time you do something that requires choosing an account--such as creating a new email--you're presented with a list of the available accounts. It's a great feature that works exactly as you'd expect.

(In fact, it's even better. You can mix and match between linked and non-linked email accounts on your phone, organizing them however you see fit in whatever combination of linked and non-linked inboxes you like. You might want to create a linked inbox with just personal email, for example, and then keep your single work account separate. However you choose to manage your mail, Windows Phone 7.5 can accommodate it.)

Using Linked Inbox with consolidated email accounts

OK, fair enough. But what does this have to do with email consolidation?

To make this easier to understand, let's say you have two email accounts, one with Gmail and one with Hotmail. You've configured Gmail to forward all of your email to Hotmail (as I've done) and you've configured Hotmail to be able to send new email as it were Gmail, somewhat masking the change you've made from others (which I've also done). Remember: Both of these configuration changes are detailed inEmail Consolidation: How To Forward Email To Other Accounts.

OK, that's fine for your PC-based email activities. And when you configure your Hotmail account on Windows Phone, it will of course show whatever Gmail email arrives at Hotmail since that mail is automatically being forwarded. But it has no knowledge of Hotmail's web-based ability to send email as if it were Gmail.

Fortunately, there's a way around this limitation. And that way, of course, is Linked Inbox.

To configure Windows Phone to be able to send email from both your Hotmail and Gmail account, you'll need to configure both accounts on the phone. If you've really stopped using Gmail for the most part, you might also want to disable Gmail's Contacts, Calendar, and/or Tasks from Settings -> Email + Accounts + Gmail as well. But leave Email enabled, since we need the ability to send mail.

Windows Phone Email + Accounts settings

Once this is complete, open the Hotmail tile on your Start screen and tap Moreand then Link Inboxes, as described above. You'll see Gmail in the list of "other inboxes" that you can add to the Linked Inbox view. Select Gmail, tap Done (or Back, if you had previously created the linked inbox) to finish.

Linked Inbox on the Start screen

Now, Hotmail will of course continue to display the email you're forwarding automatically from Gmail. But when you tap the New (Email) app bar button, you'll also have the choice to send email from either HotmailorGmail, just as you do on the web.

Choose an account for sending a new email

Problem solved.

After much futzing around, I've personally chosen to have a single linked inbox view of all my email on Windows Phone, and I've logically named it Email. But the beauty of this system, again, is that you can configure it however you'd like. Have fun!